The differences between “第” and “头”

Both第一次[di4 yi1 ci4] and 头一次[tou2 yi1 ci4] mean “the first time”. However, there are several basic differences between the usage of 第 and 头 which lead to different meanings, which will be with several example sentences.

To begin with, 第 focuses on the previous times while 头 indicates the initial time, therefore 第三次 and 头三次 have dissimilar meanings. 第三次 means the third time whereas 头三次means the first three times.

考试[kao3 shi4] (exams) 成绩[cheng2 ji4] (results)

EX：这是我第三次的考试成绩。 This is the result of my third exam.

EX：这是我头三次的考试成绩。 These are the results of my first three exams.

Secondly, when 第 and 头 are coupled with 几[ji3] (how many), the usages of the two phrases are different. 第几次 which means “how many times” is usually used in a question sentence. 头几次 meaning “the first few times” can be used in either a question sentence or a declarative sentence.

EX: 这是你第几次考试？ How many times have you taken the exam?

EX：这是你头几次考试？ Is this one of your first few exams?

EX：这是你头几次考试。This is one of my first few exams.

Finally, in Chinese “the first two times” is expressed as 头两次 instead of 头二次。However, 第二次is acceptable.